The present invention relates to an engine hood structure for automobiles, and specifically, relates to an engine hood structure for automobiles which has necessary tensile rigidity, bending rigidity and torsional rigidity, an engine noise absorbing characteristic and an excellent impact absorbing characteristic.
An engine hood for automobiles includes an hood outer panel and an hood inner panel constituted of a plurality of beam members in order to provide necessary tensile rigidity, bending rigidity and torsional rigidity. A steel plate has been conventionally used as a material for an automobile engine hood. Recently, aluminum alloy plates, such as Japanese Industrial Standard (JIS) 5000 series, 6000 series and 7000 series, are frequently used from a viewpoint of reduction in weight of the engine hood.
Further, the engine hood for automobiles has a sound insulator for reducing noise generated from the engine, which is attached to the hood inner panel. However, it is required to minimize a height of the engine hood. Therefore, there is a demand to provide an insulator having a reduced thickness and an excellent sound absorbing characteristic.
Further, if there occurs a collision of an automobile with a pedestrian, the pedestrian is lifted up such that the head or shoulder of the pedestrian will be hit against the hood outer panel of the engine hood. Therefore, in the engine hood for automobiles, it is required to ensure a characteristic of protecting the head or shoulder of the pedestrian upon the occurrence of collision. In order to improve the pedestrian protecting characteristic, there have been proposed technologies including an arrangement of an impact absorbing member that is made of a synthetic resin material and disposed between an engine hood and a chassis component within an engine compartment. Japanese Patent Application First Publication No. 2000-203378 describes such an arrangement of an impact absorbing member. Further, Japanese Patent Application First Publication No. 2003-054449 describes a hood inner panel having a plurality of projections and an irregular shape part formed on an outer surface of each of the projections. The irregular shape part is adapted to allow deformation of the outer surface of the projection when a load is applied to the projection. Further, Japanese Patent Application First Publication No. 2003-205866 describes an hood inner panel having corrugated beads and convex shaped portions. Japanese Patent Application First Publication Nos. 2003-252246 and 2003-261070 describe a reinforced panel structure. Further, there have been proposed a technology of developing an air bag onto an engine hood upon detecting a collision by means of a sensor mounted to a vehicle, and a technology of lifting up an engine hood to increase a space between the engine hood and an engine compartment and thereby prevent parts or members accommodated in the engine compartment from coming out from the engine compartment.